Using non-imaging optics, it is currently possible to achieve over 90% collection of visible light from a light source such as a metal halide lamp. The light can be used to couple into a fiber optic illumination system, but typically any UV energy is filtered from light directed to a fiber optic cable using absorbing or reflecting filters. This is to prevent degradation of the fiber optic cable.
One way prior art lighting systems used UV energy is by employing phosphor to convert UV energy to visible light. Phosphor conversion systems have been used in fluorescent lamps, metal halide lamps, and light emitting diodes to produce light or change the color of light. However, phosphors do not conserve the angular distribution of the driving light—the light they emit has a broader angular distribution than the light absorbed. This increase in angular distribution often reduces the brightness of phosphor-based lamps sufficiently so as to be difficult to use in efficient, compact optical coupling systems such as lighting fixtures or fiber optic illuminators. What is needed is a compact way of improving light-output quantity and quality using phosphors.
It would be desirable to provide a light collection system in which UV energy is captured and converted into visible light with phosphor. It would be desirable to provide a compact way of doing so while improving both light-output quantity and quality. This would increase the visible light provided from a light source that produces UV energy in addition to visible light. The additional visible light could be directed to a fiber optic cable without causing UV damage to the cable.